Development and validation of a bioanalytical method to measure fluazuron in bovine plasma and its application in pharmacokinetic studies

Resumo

Fluazuron is an insect growth regulator belonging to the benzoylphenylurea class that is marketed for the control of cattle ticks. Although growth regulators are a widely studied class, the number of papers describing analytical methods for determining fluazuron in plasma samples is small. To evaluate the pharmacokinetic characteristics of fluazuron in cattle, a sensitive and simple LC-UV method was developed and validated. The experimental conditions were optimized by comparative study of three extraction methods: LLE, SPE and MSPD. The chromatographic separation was achieved in a Kromasil C18 column, with mobile phase of acetonitrile: water (80:20, v/v) at flow rate of 1.0 mL min-1. The method was fully validated according to the requirements of ANVISA within the range of 20–150 ng mL-1 (r > 0.99). The inter/intra-assay precision and accuracy were ≤ 9.48% (CV) and ≤ 10.3% (RSE) respectively. As results, the pharmacokinetic parameters Cmax (74.4 ± 3.52 ng/mL), AUC0-t (1007 ± 33.5 ng*d mL-1) and t1/2 (14.6 ±2.97 d) for fluazuron after topical administration on cattle were obtained. The bioanalytical method was suitable for the application in pharmacokinetic studies, since LLOQ values for fluazuron allowed the quantification to reach AUC0-t greater than 80% of AUC0-∞.